CVE-2026-15754
Low
No strong exploitation signal.
CVSS base
4.2
MEDIUM
CVSS:3.1/AV:N/AC:H/PR:H/UI:R/S:U/C:N/I:H/A:N
EPSS — probability of exploitation (30 days)
0.2%
4.5th percentile
CISA KEV
Not listed
Weakness / dates
CWE-863
Published 2026-08-17 · modified 2026-08-18
CVSS breakdown
CVSS:3.1/AV:N/AC:H/PR:H/UI:R/S:U/C:N/I:H/A:N
| Attack Vector | N | Network |
| Attack Complexity | H | High |
| Privileges Required | H | High |
| User Interaction | R | Required |
| Scope | U | Unchanged |
| Confidentiality | N | None |
| Integrity | H | High |
| Availability | N | None |
Timeline
- 2026-08-17 — Published (NVD)
- 2026-08-18 — Last modified (NVD)
Description
Mattermost versions 11.7.x <= 11.7.6, 11.8.x <= 11.8.3 The access control policy unassign endpoint fails to re-validate that each target channel still belongs to the requesting admin's team, which allows an authenticated team administrator to remove ABAC (attribute-based access control) policy assignments from channels outside their team via the policy unassign API after a channel has been moved to another team.. Mattermost Advisory ID: MMSA-2026-00718